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Electrical and structural properties of Ti/Al‐based contacts on AlGaN/GaN heterostructures with different quality
Author(s) -
Greco Giuseppe,
Iucolano Ferdinando,
Bongiorno Corrado,
Di Franco Salvatore,
Lo Nigro Raffaella,
Giannazzo Filippo,
Prystawko Pawel,
Kruszewski Piotr,
Krysko Marcin,
Grzanka Ewa,
Leszczynski Michał,
Tudisco Cristina,
Condorelli Guglielmo Guido,
Roccaforte Fabrizio
Publication year - 2015
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201431636
Subject(s) - ohmic contact , materials science , annealing (glass) , heterojunction , contact resistance , optoelectronics , electrical resistivity and conductivity , electrical contacts , metal , stack (abstract data type) , condensed matter physics , layer (electronics) , nanotechnology , composite material , metallurgy , electrical engineering , engineering , computer science , programming language , physics
In this work, the electrical and structural properties of Ti/Al contacts on AlGaN/GaN heterostructures with a different crystalline quality were investigated. In particular, the sample with a lower defects density required a higher temperature (800 °C) to obtain Ohmic contacts, while the more defective sample showed Ohmic behaviour at lower annealing temperature (500 °C). The susceptibility to oxidation of the metal stack upon annealing has been monitored by chemical analyses. Moreover, the temperature dependence of the contact resistance of the Ti/Al annealed contacts revealed that the interface current transport mechanism depends on the material quality. These results were attributed to the presence of V‐shaped defect close to the surface of the AlGaN barrier layer. A nanoscale electrical analysis demonstrated a preferential current conduction through these defects, which indeed plays a relevant role for the formation of the Ohmic contact.